Mechanical Thrombectomy in Ischemic Strokes; the MR CLEAN trial

Berkhemer et al report in NEJM the results of a Multicenter Randomized Clinical Trial of Endovascular Treatment of Acute Ischemic Stroke in the Netherlands (MR CLEAN) that included patients with severe stroke and proximal-vessel occlusion.  The patients with acute ischemic stroke were randomly assigned to receive intra-arterial treatment plus usual care or usual care alone. Eligible patients had a proximal arterial occlusion in the anterior cerebral circulation that was confirmed on vessel imaging and could be treated within 6 hours after the onset of symptoms.

The primary outcome was evaluated based on the modified Rankin scale score at 90 days; this categorical scale measures functional outcome, with scores ranging from 0 (no symptoms) to 6 (death).

The study involved 500 stroke patients whose mean age was 65 years (23-96).  They were treated at 16 medical centers in the Netherlands with 233 assigned to intraarterial treatment while 267 to usual care alone.   Before the randomization 445 of (89.0%) were treated with intravenous alteplase, a tissue plasminogen activator. Retrievable stents were used to snare and remove the thrombus in 190 of the 233 patients (81.5%) assigned to intra-arterial treatment.  There was an absolute difference of 13.5 percentage points in the rate of functional independence (modified Rankin score, 0 to 2) in favor of the intervention (32.6% vs. 19.1%) after three months. There were no significant differences in mortality or the occurrence of symptomatic intracerebral hemorrhage about 19% in both groups at one month.

They concluded that in patients with acute ischemic stroke caused by a proximal intracranial occlusion of the anterior circulation, intra-arterial treatment administered with a mechanical device within 6 hours after stroke onset was effective and safe.